The Foundation Of Voice Leading 3rds 6ths

The goal of this lesson is to plant a seed in your mind that you can go off and develop on your own.
Voice leading is about moving between chords fluidly, and know exactly what notes to change, how many need to change,
For instance, without thinking about it, do you know that the difference between F and Dm is one note?
It's D.
Did you know that there are 9 different ways to play this on the fretboard? Or exactly where all of those places are?
Are you beginning to see how powerful an understanding of voice leading might be?
Without further ado, I introduce to a downward 3rds diatonic progression.

Now, looking at these chords. There's some important things to notice right away. This is C major. And it's diatonic, so all the chords only use the notes of C major.
The most important thing to notice for the sake of this lesson is that only one note changes at a time.
Illustrated here, I'm only notating the note which changes as the chords descend in thirds.

Showing it this way illustrates an interesting pattern. For some reason, getting from chord to chord means adding a note on a string.. and then the string below it... and then the 3rd string.. and then starting over with the first. But how do you know which string to add a note on?
The answer is: You have to know what inversion the previous chord was in.
For those who don't know, the chord inversion answers the question "Which note is the root?" so in a C major triad, which note is C?
If it's a root chord, then C is the lowest note. If it's a FIRST inversion, then C is the highest note. If it's a SECOND inversion, then C is the middle note.
Now, it's important to know simply which notes are which on the fretboard to figure this out. But you can also tell by the shape.
These are the shapes of root, 1st, and 2nd inversion Major triads.

root 1st 2nd
-1----1----1--
-3----1----2--
-3----2----1--

These just happen to be Bb Major, F Major and Db Major, I just want to show the shapes so they're obvious, and recognize that the Root note is on the 3rd string for root position, the 1st string for 1st inversion, and the 2nd string for 2nd inversion.
Now that we can see that we're changing one note at a time as we move in downward thirds, I have a few things to point out to you, and from there I will end the lesson with questions for you to make sure you can answer for yourself. My part being providing you the tools you need to do so.
If we go back to that progression, I want you to see that the note we're adding each time we change chords is the root. And it's ALWAYS the root.

I also want you to see that this progression shows you how chords relate to one another.
For instance,
Em, and Am each have two notes in common with C.
F and G each have one note in common with C.
Dm and Bdim have NO notes in common with C.
The last thing I want to show you is the "math" sequence. Let's correlate the Notes of C major with numbers to show their distance from C (also so we can translate this to the other 11 keys).

1-2-3-4-5-6-7
C-D-E-F-G-A-B

To get back to C, a downward thirds progression goes through this sequence: 1-6-4-2-7-5-3-1
So that's why for C major, it goes C, Am, F, Dmin, Bdim, G, Em, and back to C.
This should be enough information to plant the seed.
Here's the questions:
Do you know the other two sequences? 1st inversion to 2nd, and root to 1st inversion. (I showed you 2nd inversion of C to root inversion of C)
Can you play the sequence backwards?
Can you "skip a step" moves two notes at a time? And what would that mean?
If you "skip 2 steps" and move 3 notes? What does that mean?
Can you modify these shapes to play the progression on the other 3 string sets: 2-3-4, 3-4-5, 4-5-6.
Lastly... and the biggest leap from the information at hand... is playing the progression vertically across string sets.
If this sounds daunting, it's because it is. There's a million little details to learn. Each step is pretty easy. Cumulatively, having a grasp of this information can make you a ridiculously good guitar player. Hell, having a grasp of all this would make you a pretty damn good musician in general.
If you're at a point in your playing where this lesson is interesting enough to focus on. Do some work with it each day. Play it and write down on paper how the shapes move. It's one of those things which can quickly turn into an obsession. Don't push it too hard, or it will turn into a headache. If you try to wrap your head around everything that's going on here at once... your head will hurt. It sucks.. there really is that much information. And the human brain can only really deal with it at a subconscious level.
A little at a time.
Cheers! Ryan